P0979 2015 GMC Sierra Code - Shift Solenoid Valve 3 Control Circuit Low Voltage
Quick Answer
The Transmission Control Module (TCM) high side driver 1 supplies 12 V to pressure control solenoid valve 3. Common causes include Faulty Shift Solenoid Valve 3, Shift Solenoid Valve 3 harness is open or shorted, Shift Solenoid Valve 3 circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P0979 2015 GMC Sierra indicates Shift Solenoid Valve 3 Control Circuit Low Voltage.
- Common causes
- Common causes include Faulty Shift Solenoid Valve 3, Shift Solenoid Valve 3 harness is open or shorted, Shift Solenoid Valve 3 circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P0979 2015 GMC Sierra Description
What are the Possible Causes of the DTC P0979 2015 GMC Sierra?
- Faulty Shift Solenoid Valve 3
- Shift Solenoid Valve 3 harness is open or shorted
- Shift Solenoid Valve 3 circuit poor electrical connection
- Faulty Transmission Control Module (TCM)
How to Fix the DTC P0979 2015 GMC Sierra?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0979 2015 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Frequently Asked Questions about P0979 2015 GMC Sierra Code
1. What does the OBDII code P0979 mean on a 2015 GMC Sierra?
P0979 indicates a low voltage issue in the control circuit for Shift Solenoid Valve 3, which helps manage gear shifting in the transmission.
2. What are the common symptoms of code P0979 in a 2015 GMC Sierra?
Symptoms may include harsh or erratic shifting, stuck gears, limp mode activation, or an illuminated check engine light.
3. What causes the P0979 code on a GMC Sierra?
The most common causes are a faulty shift solenoid, damaged wiring or connectors in the circuit, low transmission fluid, or a malfunctioning transmission control module (TCM).
4. Can low transmission fluid trigger the P0979 code?
Yes, insufficient or contaminated transmission fluid can affect solenoid performance and lead to this code.
5. How do I diagnose the P0979 code on my 2015 GMC Sierra?
Start by inspecting the transmission wiring and connectors for damage, checking the solenoid's resistance, and testing the voltage at the solenoid circuit.
6. How do I fix the P0979 code on my GMC Sierra?
Repairs may include replacing the faulty shift solenoid, repairing damaged wiring, cleaning or reconnecting corroded connectors, or addressing low transmission fluid.
7. Is it safe to drive with the P0979 code on a 2015 GMC Sierra?
Driving with this code can lead to erratic shifting and potential transmission damage, so it’s best to address the issue promptly.
8. How much does it cost to repair the P0979 code on a GMC Sierra?
Costs can vary, but replacing a shift solenoid typically ranges from $200 to $400, while wiring repairs can cost less depending on the extent of the damage.
9. Can a bad TCM cause the P0979 code in a 2015 GMC Sierra?
Yes, a malfunctioning Transmission Control Module can cause improper voltage regulation in the solenoid circuit, triggering this code.
10. Will clearing the P0979 code fix the problem permanently?
No, clearing the code will only reset the warning temporarily. The underlying issue must be diagnosed and repaired to prevent the code from returning.
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